de.xwic.appkit.core.model.EntityModelFactory.java Source code

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Here is the source code for de.xwic.appkit.core.model.EntityModelFactory.java

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/*******************************************************************************
 * Copyright 2015 xWic group (http://www.xwic.de)
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and 
 * limitations under the License.
 *  
 *******************************************************************************/
package de.xwic.appkit.core.model;

import java.lang.reflect.Proxy;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import de.xwic.appkit.core.dao.IEntity;

/**
 * Creates IEntityModel objects. The model is a dynamicaly generated proxy that implements
 * both the IEntityModel interface as the interface(s) of the given entity. All modifications
 * must be made against the proxy class. 
 * 
 * The entityModel keeps a map of modified properties that are written to the base
 * entity on commit.
 * 
 * @author Florian Lippisch
 */
public class EntityModelFactory {

    /** logger */
    protected static final Log log = LogFactory.getLog(EntityModelFactory.class);

    private static ClassLoader classLoader = null;

    static {
        classLoader = new EntityModelFactory().getClass().getClassLoader();
    }

    /**
     * Returns true if the specified entity is a EntityModel implementation.
     * @param entity
     * @return
     */
    public static boolean isModel(IEntity entity) {
        return (Proxy.isProxyClass(entity.getClass())
                && Proxy.getInvocationHandler(entity) instanceof EntityModelInvocationHandler);
    }

    /**
     * Returns the original entity.
     * @param entityModel
     * @return
     */
    public static IEntity getOriginalEntity(IEntity entityModel) {
        if (!Proxy.isProxyClass(entityModel.getClass())) {
            throw new IllegalArgumentException("entity is not an entityModel");
        }
        Object oIh = Proxy.getInvocationHandler(entityModel);
        if (!(oIh instanceof EntityModelInvocationHandler)) {
            throw new IllegalArgumentException("entity is a proxy but not an entityModel");
        }
        EntityModelInvocationHandler emIh = (EntityModelInvocationHandler) oIh;
        return emIh.getEntityModelImpl().getOriginalEntity();
    }

    /**
     * Creates a new entity model based upon the specified entity.
     * @param entity
     * @return
     * @throws EntityModelException 
     */
    @SuppressWarnings("unchecked")
    public static IEntityModel createModel(IEntity entity) {

        // create model and InvocationHandler
        Set<Class<?>> interfacesSet = new HashSet<Class<?>>();
        Class<? extends IEntity> clazz = entity.getClass();
        interfacesSet.add(IEntityModel.class);

        // recursivly add all interfaces
        Class<?> c = clazz;
        while (c != null) {
            Class<?>[] orgInterfaces = c.getInterfaces();
            for (int i = 0; i < orgInterfaces.length; i++) {
                interfacesSet.add(orgInterfaces[i]);
            }
            c = c.getSuperclass();
        }
        Class[] interfaces = new Class[interfacesSet.size()];
        int idx = 0;
        for (Iterator<Class<?>> it = interfacesSet.iterator(); it.hasNext();) {
            interfaces[idx++] = it.next();
        }

        EntityModelInvocationHandler ih = new EntityModelInvocationHandler(entity);
        return (IEntityModel) Proxy.newProxyInstance(classLoader, interfaces, ih);

    }

    /**
     * Set the classLoader to be used.
     * @param classLoader
     */
    public static void setClassLoader(ClassLoader classLoader) {
        EntityModelFactory.classLoader = classLoader;
    }

}